This invention relates to a novel process for the preparation of 2-aminoalkanesulfonic acids (commonly known as taurines). More specifically, this invention relates to the preparation of the metal salts of the 2-aminoalkanesulfonic acids which can be converted to the acid form readily.
2-Aminoalkanesulfonic acids are useful in treating epilepsy and as intermediates in the preparation of N-acyl-N-alkyltaurates which are anionic surfactants with several advantageous properties.
2-Aminoethanesulfonic acid occurs in the tissues of various lower animals and in the secretions of higher animals. Common sources are ox bile and the large muscle of the abalone.
2-Aminoethanesulfonic acid has been synthesized by several methods. Kolbe, Ann., 122, 42 (1862), converted isethionic to 2-chloroethyl sulfonyl chloride, hydrolyzed this product to 2-chloroethyl sulfonic acid and obtained 2-aminoethanesulfonic acid by treating the 2-chloroethyl sulfonic acid with aqueous ammonia. In this process, the separation of the product from ammonium chloride is quite troublesome.
Gabriel, Ber., 21, 2667 (1888), prepared 2-aminoethanesulfonic acid from ethyleneimine and sulfur dioxide, and from 2-mercaptothiazoline by oxidation with bromine water, Ber., 22, 1153 (1884). Reychler, Bull. Soc. Chim. Belg., 32, 247 (1923), prepared 2-aminoethanesulfonic acid from bromoethylamine and ammonium sulfide. These methods require 2-bromoethylamine as a starting material and are not useful for the preparation of large amounts of the product.
Auzies, Chem. Zentr., 82 (II) 1433 (1911), prepared 2-aminoethanesulfonic acid by sulfonation of acetaldehyde with chlorosulfonic acid, followed by the reaction with ammonia to form the amido compound and finally by reduction to the amino compound. These reactions are complex.
Marvel et al., "A Synthesis of Taurine", J.A.C.S., 49, 1833 (1927) teach that 2-bromoethyl sulfonyl chloride is hydrolyzed to the acid form, then treated with aqueous ammonia. The product is separated by crystallization from dilute alcohol.
Sexton, U.S. Pat. No. 2,693,488, teaches that aminoalkanesulfonic acids are prepared by reacting an aqueous solution of ammonium hydroxide or an alkylamine with the metallic salt of the corresponding hydroxyalkanesulfonic acid.
The foregoing prior art processes described have several disadvantages. Some of the processes prepare salts as by-products. Many of the processes involve complex syntheses. The prior art processes usually result in low yields of the product. Furthermore, the reactants used are quite expensive, which makes commercial use of the 2-aminoethanesulfonic acid very costly.
What is needed is a process for the preparation of 2-aminoalkanesulfonic acids in which salts are not produced as by-products. What is further needed is a process which is relatively simple that gives high yields of products. Furthermore, a process in which the reactants are relatively inexpensive is needed.